Home › Carrier › Air Conditioners › 16
Carrier Air Conditioner 16 Error Code
Lost communication with the Infinity control on Carrier air conditioners.
CarrierAll Carrier air conditioner codes
On a communicating Infinity system the outdoor board, the indoor unit and the wall control share a data link. Code 16 means the outdoor unit has stopped hearing from the user interface. Carrier points to the wiring between the control and the indoor and outdoor units.
Compatible models
Infinity 24ANB7 air conditioners and 25HNB6/25HNB9 heat pumps, when wired to an Infinity user interface.
Also shown as
A green COMM light sits next to the amber one on Infinity boards. It goes dark when no valid message has arrived for 2 minutes and comes back on with the next one. Units wired to an ordinary thermostat don't use this link.
Difficulty
Start with the safe checks below; a worn part may need replacing.
Not sure you are reading the code right? See how to read Carrier air conditioner codes.
How to fix Carrier 16
Check the wall control
Look at the Infinity control on the wall. A blank screen suggests the indoor unit has lost power, so check its breaker and the service switch next to the furnace or fan coil.
Power the whole system down together
Turn off the furnace or fan coil breaker and the outdoor disconnect, wait about five minutes, then switch both back on.
Think back to recent work
A new thermostat, wall repairs near the control or digging near the outdoor wiring can disturb the low-voltage cable. Mention any of that to the technician.
When to call a technician
If the link doesn't recover after a full power cycle, a technician needs to trace the communication wiring between the control and both units and check the boards.
Parts linked to 16
These are the parts most often behind this code. Tap one to see what it does and the signs it is failing.
- Indoor-outdoor communication cable
- Outdoor control and inverter board
- infinity wall control
Order parts by your full model number so they fit.
Frequently asked questions
Which Carrier models show the 16 code?
Infinity 24ANB7 air conditioners and 25HNB6/25HNB9 heat pumps, when wired to an Infinity user interface.
Can I fix Carrier 16 myself?
Often. The first steps above are safe checks a homeowner can do. If they don't clear 16, the cause is likely a worn part that needs replacing.
Other Carrier air conditioner codes
- Solid / 1 / 2Status light showing normal operation
- 25Model plug missing or wrong
- 31 / 84High-pressure switch tripped or locked out
- 32 / 83Low-pressure or discharge temperature trip
- 45Outdoor control board fault
- 46Brown-out: supply voltage too low
- 47No 230-volt power reaching the outdoor unit
- 53 / 55 / 56Outdoor air or coil sensor fault
- 71 / 72 / 81 / 82Compressor thermal cutout or lockout
- 73 / 74Contactor stuck closed or not closing
- E1Ductless indoor and outdoor units not talking
- ECRefrigerant leak detected
- E3 / F5Ductless fan speed out of range
- E4 / E5 / F1 / F2 / F3Ductless temperature sensor open or shorted
- F0 / P1Ductless overcurrent or voltage protection
- P3Too cold outside to heat
- P5Multi-zone mode conflict
- CL / dFFilter reminder or defrost in progress
Last reviewed 2026-10-22. Codes and steps can vary by model; check your owner's manual.